Fix NPE when car volume group info is not available

Car volume group info is not supported if the car audio
framework is configured in legacy mode. In such cases, the
volume definitions need to be queried directly through car
audio manager apis.

Bug: 332389708
Test: Manual
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:62f986a2e5ae96760a1bd145700f36cd40123e6b)
Merged-In: I474db48e8ff8f3d3e2794d13ec20f87fe94c57ad
Change-Id: I474db48e8ff8f3d3e2794d13ec20f87fe94c57ad
1 file changed